The Supermarine Spitfire is a British single-seat fighter aircraft that was used by the Royal Air Force and many other Allied countries before, during and after World War II. The Spitfire was built in many variants in greater numbers than any other British aircraft. The Spitfire continues to be popular among enthusiasts; about 54 remain airworthy.

During the Battle of Britain, from July to October 1940, the Spitfire was perceived by the public to be the main RAF fighter, though the more numerous Hawker Hurricane shouldered a greater proportion of the burden against the Nazi German air force, the Luftwaffe. Spitfire units, however, had a lower attrition rate and a higher victory-to-loss ratio than those flying Hurricanes because of its higher performance. Spitfires in general were tasked with engaging Luftwaffe fighters (mainly Messerschmitt Bf 109E series aircraft which were a close match for the Spitfire) during the Battle.

After the Battle of Britain, the Spitfire superseded the Hurricane to become the backbone of RAF Fighter Command, and saw action in the European, Mediterranean, Pacific and the South-East Asian theatres. Much loved by its pilots, the Spitfire served in several roles, including interceptor, photo-reconnaissance, fighter-bomber and trainer, and it continued to serve in these roles until the 1950s. The Seafire was a carrier-based adaptation of the Spitfire which served in the Fleet Air Arm from 1942 through to the mid-1950s. Although the original airframe was designed to be powered by a Rolls-Royce Merlin engine producing 1,030 hp (768 kW), it was strong enough and adaptable enough to use increasingly powerful Merlins and, in later marks, Rolls-Royce Griffon engines producing up to 2,340 hp (1,745 kW); as a consequence of this the Spitfire's performance and capabilities improved over the course of its life.